The transmissible spongiform encephalopathies (TSEs or prion diseases)are fatal untreatable neurodegenerative diseases such as scrapie, Creutzfeldt-Jakob disease (CJD), bovine spongiform encephalopathy and chronic wasting disease (CWD). TSE pathogenesis involves the accumulation of an abnormal misfolded protein, called PrPres, in infected hosts. We and others previously had identified pentosan polysulfate, tannic acid, tetracycline HCl as strong blockers of PrPres accumulation. In this study, we compared prion infection rates among mule deer (Odocoileus hemionus) receiving pentosan polysulfate, tannic acid, tetracycline HCl, or no treatment 14 days before to 14 days after (dpi) oral inoculation with tonsil tissue homogenate. All deer were infected, but the rapid disease course (230-603 dpi) suggested our challenge was overwhelming and that the drugs were not able to protect against such a high-titered inoculum of CWD infectivity.